The 5 elements we know of so far: Wind, Thunder, Fire, Earth, and Water. Classic elements are or would incorporate: Time/Space, Light, Darkness, Heaven/Void/Wind/Air/Thunder, Water, Fire, and Earth. The Rinnegan can utilize all 6. I suspect the 6th element would be something like Chaos or Darkness. Probably Darkness considering how Pein is evil. Yet, there is technically 7, I say. The 5 we know of, Darkness and Light. Since Pein and Madara are currently the Big Bad Guys (as well Sasuke being in here), the Hero and Heroine are the vessels of Light.

the other jutsu is kinda rare. it's crystal. such as the crystal style user guren guren

i thought is was a kekkai gekkai (bloodling limit).

since you mentioned the bloodline limit in reguards to gurens crystal abilities i watched an episode and its actually an element. before she uses a technique she says "Shouton" meaning crystal element, also she is reffered to "the crystal element user"